The present invention relates generally to an antenna for radiating ultra wide bandwidth (UWB) radio frequency (RF) pulses for use in communications systems and sensors such as radars. More particularly, the present invention relates to an antenna for impulse radar.
As is known in the art, impulse radar is presently being used in a variety of radar systems in order to determine the location of aircraft, ground vehicles, people, mines, buried pipes, and faults in roadways, tunnels, leaking buried pipes, etc. However, a problem that arises in connection with the use of impulse radar is the reflection of the transmitted pulse by the transmitting antenna itself. That reflection causes an exponentially decaying oscillation as the pulse reflects back and forth between the transmitter and the antenna. In some instances, that oscillation can be so strong and last so long that it masks the intended target.
Although some common methods for minimizing the problem of transmitted pulse reflection by the transmitting antenna have been developed, such methods have been, to date, less than satisfactory. Common methods for minimizing that problem are to add a loss to the transmission line, add a loss to the antenna or to design a transmitter that will terminate the reflected wave. Adding losses to either the transmission line or the antenna have the disadvantage of wasting a portion of the transmitter power. Designing a transmitter to terminate the reflected wave has, to the present time, resulted in inefficient and bulky designs, which are unsatisfactory. Therefore, there still exists a need in the art for an antenna that minimizes losses while at the same time maintains high return loss.